The overall objctive of this work is to analyze the genetic relationships of the various populations of the Common Hose Mosquito present in the Boston area. By comparing the electrophoretic mobility ofselected isozymes, we shall determine (1) whether the autogenous, anautogenous and rural formsmay be characterized, 2) whether these populations may be genetically isolated, 3) if so, wether isolation is absolute, and 4) whethe one population may possess more genetic variability than others. We shall study the blood-feeding habits of each population and determine whether man-biting may be associated with certain populations or combinations of populations. A manual will be prepared describing procedures for applying the polyacetate strip method of electrophoresis to populations of mosquitoes.